by John Shinal, Special for USA TODAY

by John Shinal, Special for USA TODAY

HALF MOON BAY, Calif. - Several of the largest private mobile advertising companies are among a group of start-ups testing investors' appetites for tech IPOs by using a new confidential securities filing created last year, according to several people familiar with these companies' plans.

While these sources declined to name the specific companies involved, citing confidentiality agreements, mobile ad start-ups with enough annual revenue and venture-capital financing to pull off such an offering include Flurry, InMobi, MoPub and Jumptap.

The IPO candidates are among 175 U.S. companies from a range of industries that have filed such Draft Registration Statements (or DRS filings) since the JOBS Act of 2012 loosened capital-raising rules for emerging growth companies.

The securities registrations - a tentative half-step toward an initial public offering - have come as fund managers who lost big money in the disastrous Facebook IPO are finally warming up to growing tech companies again.

"After the social-media bubble popped, investors became more cautious about consumer Internet companies, but they're starting to come back," says Doug Chu, senior vice-president of NYSE Euronext and head of that exchange's Silicon Valley office.

Evidence of that, says Chu, can be seen in the recent IPO of the China-based e-commerce company LightInTheBox, which raised $79 million this month by selling 8.3 million American Depositary Shares (a kind of U.S. stock for foreign companies) at $9.50 each.

As of Friday, the shares were trading at around $15 a share.

That gave the stock a better-than-average performance compared with the 45 other tech companies that have gone public so far this year, says Chu, speaking at a technology conference here last week sponsored by Bloomberg.

That suggests the managers of big mutual funds, pension and hedge funds are warming up to the types of tech companies already in the IPO pipeline, including mobile ad start-ups that help online marketers place ads on smartphones and tablets.

"Investors are looking for growth," says Mitchell, who also sits on the board of Silicon Valley Bank, which provides loans and other financing to tech companies, and who spoke on the same conference panel as Chu.

For pension and mutual fund managers looking for growth in the tech industry, mobile advertising is one market where they're sure to find it.

Mobile ad spending more than doubled, to $3.4 billion in 2012 from a year earlier, says the Interactive Advertising Bureau, an industry trade group.

That far outstripped the 15% annual growth for online advertising overall, yet mobile ads still comprise only a tenth of a $37 billion market.

Facebook said in April that mobile revenue contributed 30% of its $1.5 billion in first-quarter ad revenue. Given the overall growth of mobile, that means Facebook will sell more than $2 billion worth of mobile ads this year.

Wall Street analysts estimate Google garnered 10% to 15% of its $14 billion in first-quarter revenue from mobile ads, with JMP Securities of San Francisco pegging the figure at 14%. If accurate, that means Google will sell at about $8 billion worth of mobile ads this year.

Google is among the top sellers of mobile ads - along with Facebook and Apple - thanks in part to its $750 million acquisition of mobile start-up AdMob in 2009.

Now, several of AdMob's rivals from among Flurry, InMobi, MoPub and Jumptap are testing the IPO waters, looking to raise more cash to help attack this fast-growing market.

InMobi has already raised $220 million from investors, including a $200 million late-stage round in 2011 from SoftBank and Masayoshi Son, the veteran Japanese investor who's made big money on Yahoo and other tech firms over the last 15 years.

In May, MoPub - whose co-founder and CEO Jim Payne is a former AdMob executive - said its annual revenue run rate had reached $100 million. One of the company's board members is Rich Wong of VC firm Accel Partners, one of the first investors in Facebook and AdMob.

Flurry, based in San Francisco, raised $25 million late last year in a Series D round from investors that included Crosslink Capital, a late-stage firm that had also invested in Pandora Media and Ancestry.com shortly before those tech companies went public.

When the company raised that round, its CEO, Simon Khalaf, was quoted by several news organizations as saying the company's annual revenues were in the range of $80 million to $100 million - and that Flurry was considering an IPO in the second half of 2013.

Flurry has raised just over $50 million to date from a group of investors including Draper Fisher Jurvetson, First Round Capital, InterWest Partners, Menlo Ventures, Union Square Ventures and Draper Richards.

Executives of companies that have made a confidential draft (DRS) filing can meet with potential IPO investors beginning 21 days later, to gauge demand for their shares without letting rivals such as Google or Facebook know of their plans to raise a war chest.

Even so, there's no guarantee that any of these companies will be able to execute a successful public offering this year, especially if the broader U.S. stock market turns south, spooking IPO investors.

In fact, the first U.S.-based mobile ad company to conduct an IPO has stumbled badly in the public markets, even while the broader market for tech stocks had been surging (before this week!).

Millennial Media, based in Baltimore, raised $133 million in a March 2012 IPO that priced its shares at $13 each. The shares doubled to $26, and then some, in their first day of trading - giving the company a market value just under $2 billion on its first day in the public markets.

But that was before the Facebook post-IPO stock plunge of 40% made clear that investors understood mobile advertising would not be as profitable as desktop advertising, at least not right now.

Both Facebook and Google have, over the past 12 months, changed the way they sell advertising to help offset the trend, by selling mobile ads packaged with desktop ads.

But while Google has been effective in slowing the rate of decline in its cost-per-click metric - reining it in from a 16% year-over-year drop last summer to a 4% fall in the first quarter - the trend is still here.

It can be seen in the financial results of Millennial Media.

While the company's revenue surged 50% to $49 million for the quarter ended in March, up from $33 million a year earlier, Millennial still posted a net loss of 5 cents a share.

While the loss was cut significantly, from 32 cents in the first quarter of 2012, the fact remains that the company was unprofitable in the quarter it went public, and it remained unprofitable a year after it.

Investors have noticed, and Millennial's shares have suffered as a result.

After touching a 52-week low of $5.87 in April, they most recently traded at around $8.50 a share, giving the company a market cap of $670 million, or 2.5 times the 2013 annual sales expected by the eight Wall Street analysts who rate the company's stock.

In other words, big-money investors who got the shares at $13 are underwater, big-time, while those who bought the stock in either of its first two trading days are sitting on more than $1 billion in collective losses.

And yet, if shares are priced right, investors may soon see some of these mobile ad companies coming to the public markets via an IPO.

"We'll see a lot of activity there (in mobile advertising)" says Lise Buyer, a former Internet analyst on Wall Street and the founding partner of Class V Group, which helps guide start-ups through the IPO process.

While she declined to name any mobile ad companies that might have filed confidential IPO documents, Buyer pegged their number at "between a half-dozen and a dozen."

John Shinal has covered tech and financial markets for 15 years at Bloomberg, BusinessWeek, the San Francisco Chronicle, Dow Jones MarketWatch, Wall Street Journal Digital Network and others.